In recent years, polymer materials are increasingly utilized in many fields. With such a tendency, in addition to properties of a polymer as a matrix, characteristics of the surface or interface of the polymer for each field have become important. For example, by using a fluorinated compound having a low surface energy as a surface modifier, there is expected the enhancement of characteristics regarding the surface control such as water-repellent/oil-repellent property, antifouling property, nonadherent property, peeling property, mold release property, sliding property, abrasion resistance, antireflection characteristics, and chemical resistance, and various such surface modifiers are disclosed.
As a disclosure regarding surface modification of a thermoplastic resin using a fluorinated polymer, for example, there are disclosed a 4-methyl-1-pentene (PMP) resin film of which mold release property is enhanced by blending a tetrafluoroethylene-ethylene copolymer (ETFE) (Patent Document 1) and a fluorine-containing polyolefin excellent in water-repellent/oil-repellent property (Patent Document 2).
As a disclosure regarding surface modification of a photocurable and thermosetting transparent resin using a fluorinated polymer, for example, there is disclosed a surface treating agent for a thermosetting epoxy resin using a fluorinated polymer having fluoropolyether (Patent Document 3) and there is disclosed that a photocurable acrylic resin containing a fluorine-containing surfactant and/or a fluorinated polymer having a cyclic structure is excellent in mold release property, and by such a resin, surface modification can be performed (Patent Document 4).
On the other hand, as a certain method for synthesizing a highly branched polymer (hyperbranched polymer), there is disclosed a method for polymerizing a monomer having two or more radical polymerizable double bonds in the presence of a radical polymerization initiator. There is disclosed a production method of a highly branched polymer by a so-called initiator-fragment incorporation radical (co)polymerization using, for example, a styrene compound having two vinyl groups (Patent Document 5, Non-patent Documents 1, 2, 3, and 4), or a methacrylic compound having two methacryl groups (Patent Document 5, Non-patent Documents 5 and 6), or an allyl compound having two allyl groups (Non-patent Document 7), or other vinyl compounds having two vinyl groups (Patent Document 5, Non-patent Documents 8 and 9), and an azo-based polymerization initiator.
However, until today, there has not been yet disclosed a method for performing surface modification of a photocurable or thermosetting transparent resin using a highly branched polymer, and particularly with respect to the above initiator-fragment incorporation-type highly branched polymer, there has been no report for a fluoroalkyl group-containing highly branched polymer having a low surface energy.